Organic electroluminescent devices used typically in optical display apparatuses can suffer from degradation or deterioration in properties by the environments such as moistures or gases. Specifically, the interface between a metal field and an organic emitting layer will be delaminated owing to moistures. Furthermore, high resistance will occur due to the oxidation of the metal, and organic materials themselves will be deteriorated by moistures or oxygen. Moreover, the organic materials and electrode materials will experience the oxidation by outgases from external or internal environments, and the organic electroluminescent device may have reduced luminous properties. Thus, the organic electroluminescent device must be encapsulated with an encapsulating composition to protect it from moistures or oxygen.
The organic electroluminescent device has been encapsulated in a multilayer structure in which a inorganic protection layer and an organic protection layer are formed. The inorganic protection layer may be formed by a plasma deposition process, which can cause the organic protection layer to be etched by plasma. When the organic protection layer is etched, the encapsulating function of the organic protection layer can be damaged. Thus, the organic light emitting device can suffer from deterioration in luminous properties and reliability.
In this regard, the background of the present invention is disclosed in Korean Laid-Open Patent Publication No. 2011-0071039 A (LG Display).